DE2041162A1 - Multi-phase motor control with overcurrent and undercurrent protection - Google Patents

Description

PATENT Attorneys ^ UH J I

dr. ing. H. NEGENDANK · dipl.-ing. H. HAUCK Dipl.-Phys. W. SCHMITZ

HAMBURG-MUNICH DELIVERY / UNGS ADDRESS: HAMBURG 36 · NEUER WALL 41

TEX ,. 30 74 28 AND 364119

TELBGB. NEGEDAPATBNT BAMBTTRO MUNICH 15 MOZARTSTR. 23

TEL.3 380Π80

TEXBGR. NEGEDAPATENT MUNICH

Hamburg, August 18, 1970

Borg-Warner Corporation,
200 South Michigan Avenue,
Chicago, Illinois βθ6θ4
(V. St. A.)

Multi-phase motor control with overcurrent and undercurrent protection ζ.

The invention is suitable in connection with various motor controls and in particular for regulating a motor, which drives a submersible pump in a deep borehole such as an oil well deeper below the surface of the earth. Typically, the motor and pump are combined into one unit that is located downhole at the pumping site itself is located. It is necessary that this remote-controlled system against undesirable operating conditions such as the absence of fluid in the wellbore, a condition known as "pump-off" will. It is equally important to protect the motor against overload or short circuit conditions in which more current is supplied to the motor than it can absorb. In addition, if only one phase line of the motor is interrupted

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or is short-circuited to another phase line or to ground, protection must be provided against the resulting Phase imbalance exist.

Considerable effort has been made to resolve these problems. A significant port step on this one Territory is in U.S. Reissue Patent 26,483 entitled "Control System for Power Units such as Electric Motors fi et the like ", issue date November 5, 1968 by the same applicant and claimed. This system does not protect against any of the aforementioned conditions, and In addition, very extensive facilities are required, e.g. a separate control relay and a control relay are required for each measuring relay own pricing device required.

The invention is therefore based on the object to provide a compact and economical motor control, ψ be eliminated by not only the above-enumerated problems, but that is also cheaper and less space is required than known arrangements, less components and an effective error-free Operation permitted.

The motor control according to the invention is suitable for regulating the feeding of a multiphase motor through a multiphase feed circuit. The system has a main switch relay with a winding and main switch contacts for the Supply of the multiphase energy to the motor. A power transformer is switched in such a way that it supplies current signals,

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each one function of the motor via a phase line supplied current are.

In accordance with the invention, in particular a display and detector unit is coupled to the current transformer. These Unit has a measuring relay for each phase circuit, which is provided with a first and a second semiconductor switch. The first semiconductor switch in each measuring relay is then conductive, when the corresponding phase current is below the previously set high value, while the second semiconductor switch in each measuring relay is conductive when the corresponding phase current is above the previously set low Worth it. A first series circuit has a first connected in series with all of the first semiconductor switches Line on, which is used to issue a first control signal, which indicates that all phase currents are below the previously set high value. One The second series circuit has a second line connected in series with all of the second semiconductor switches, which is used for this purpose serves to emit a second control signal, which indicates that all phase currents are above the · before the set low value.

Furthermore, a control circuit is provided which is a switch-on relay whose winding is in series with a power button ■ and a normally closed delay contact set is switched. A delay switch-on relay that is also provided is used to operate the delay

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contact set after the phase currents exceed the previously set exceed the low value. The winding of the delay switch-on relay is connected in parallel to form a series circuit from the closing relay winding and the delay contact set. The main switch relay winding is connected in such a way that it is dependent on the closing of a contact set of the switch-on relay can be operated to close the main switch contacts and to energize the motor. Relays are switched so that they can be actuated in the absence of the first or the second control signal to the main switch relay de-energize and switch off the motor.

In addition, a device for supplying the control is provided, which can consist of two lines that can be connected to a power source or an internal power supply.

An embodiment of the invention is explained in more detail with reference to the drawing, in which the same reference numerals in the various Figures denote the same elements and

1 is a block diagram of a motor controller connected in accordance with the invention, and FIGS. 2 and 3 are schematic circuit diagrams in which details of what is shown generally in FIG Control are shown.

The control will first be described in general. In the block diagram shown in Fig. 1 is a multi-phase Motor 15 can be switched on and off via a main switch 29 when an alternating current supply voltage is

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Voltage circuit is supplied, which consists of the lines loo, lol and Io2. This AC voltage circuit is in turn fed by closing an interrupter switch Io3, whereby AC voltage energy from the network, which is represented by lines 18, 19 and 2o, is fed to lines loo, lol and Io2., A current transformer 25 is connected so that it is a Display and detector unit Ho supplies current signals over the lines Io4, Io5 and Io6. The Ho unit is also connected via a (

Line Io7 supplied with power from a power supply unit Io8. if if all phase currents in lines loo, lol and io2 are below the set high value, the display and detector unit Ho to the control circuit 26 a first control signal via the line 112. When all phase currents are above a previously set low current value, the unit Ho also supplies a second Control signal via line 114 to the control circuit. If either the first or the second control signal disappears det, indicating a phase imbalance or other disturbance in the power line, the control circuit enters 26 via the circuit indicated by the line 113 in Activity and opens the main switch 29, causing the engine is switched off.

The invention will now be described in detail with reference to FIGS described. When the circuit breaker Io3 is closed electrical energy comes from the mains supply

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Lines 18, 19 and 2o via the input lines loo, lol and Io2 to windings 38, 39 and 4o of the current transformer 25, as well as via the contacts of the switch 29 to the polyphase motor 15, whereby this is energized. Although the current transformer 25 shown here consists of • six individual current transformers, the achieve the same mode of operation with only three transformers. Although the controls continue to be in touch here is described with a three-phase circuit, it should be readily apparent to those skilled in the art that the The teaching of the invention can be applied in the same way to other multi-phase controls.

When the breaker switch Io3 is closed, arrives One phase energy from lines lol, Io2 through the transformer 6o and the lines 61, 62 connected to the secondary winding of the transformer to the feed lines 117, for the control circuit 26. The voltage on lines 61, 62 also becomes the primary winding 121 of a step-down transformer 12o supplied, which has a secondary winding 122 with a center tap. With the top of the secondary winding

122, a resistor 123 is connected. Two Zener diodes 124, 125 are connected in series in the opposite sense, the anode of the diode 124 with the other end of the secondary winding 122, and the anode of diode 125 is connected to the end of resistor 123 is. The common connection between the resistor

123 and the diode 125 is via the line 126 with the one

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Connection of a first control relay winding 127 connected to which a capacitor 128 is connected in parallel. The line 126 is also connected to one terminal of a second control relay winding 13o connected to which a capacitor 131 is connected in parallel. A first output line 112 is from the first semiconductor switch 142 in the counter or measuring relay (meter relay) 132 led to the winding 127 of the first control relay, which is used to indicate that all phase currents are below the previously set high value. A J second output line 114 connects the second semiconductor switch I4l in the measuring relay 132 to the winding 13o des second control relay, which is used to indicate that all phase currents are above the previously set low value are located. A common line 135 connects the lower terminal of the secondary winding 122 of the power supply to the Cathodes of the light-sensitive or light-actuated controllable silicon rectifiers (four-layer switching diodes) 136 » 137 in the measuring relay 134. The measuring relay 133 has the same a silicon light actuated controllable rectifier 138 set for the low value and one for display the high value serving semiconductor switch l4o.

Inside the measuring relay 132 are two lamps 143, 144 for lighting and actuation of the light-actuated controllable silicon rectifier 14l, 142 are provided. A corresponding one Lamp pair 145, 146 is located in the measuring relay 133, as well another pair of lamps 147, 148 in the measuring relay 134. All

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Lamps 143-148 are connected in parallel between two lines 15o, 151, which in turn are connected in the power supply unit Io8 in parallel to the Zener diodes 152, 153 connected in series are. Between the center tap of the secondary winding 122 and the common connection between the line 15o and a resistor 154 is arranged in the Zener diode 152. aside from that there is a common connection by means of the line 111 between the anode of the Zener diode 153 and the anode of the

"Zener diode 124.

Although not shown in the drawing, each measuring relay two adjustable diaphragms or shutter members, one near the upper end of the measuring scale, and the other is near the lower end thereof. The adjustment of the locking position near the top the meter scale of the measuring relay 132 determines, for example, the upper current value by determining the point at which the shutter prevents the light from lamp 144 from impinging on silicon rectifier 142. In the unlit state the switch 142 is open and the control relay 127 is de-energized. It should be noted that this relay is in a first series circuit, which consists of the winding 127, the line 112 and all the semiconductor switches 142, I4o and 137 consists. There is a corresponding one second series connection of the winding 13o of the second control relay, the line 114 and all light-actuated controllable Silicon rectifiers 14l, 138 and 136.

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ORIGINAL INSPECTED

The current transformer 25 has the primary windings 38, 39 and 4o, which are arranged to determine the current strength in the lines loo, lol and Io2, respectively. the Windings 41, 42 and 43 supply via the signal lines Io4, Io5 and Io6, as well as the common line 155 corresponding Phase current signals to the rectifier bridge circuits 45, 46 and 47 of the corresponding measuring relays. Located in practice each rectifier bridge circuit within the corresponding one Measuring relays, together with the measuring movement, the lamps, the shutter members and the light-actuated controllable ones Silicon rectifiers. The rectifier circuits are only for a better understanding of the invention outside of the Measuring relay shown. Initially, only the circuit of the first phase and the measuring relay 132 will be considered. if the system is switched on and the current strength in the line loo for the first phase the previously set high value does not exceed, the lamp 144 is switched on and in turn switches the controllable silicon rectifier 142 on. ' If the currents of the other two phases are also below the previously set high value at this point in time are located, the lamp 146 switches on the light-actuated controllable silicon rectifier I4o, and the lamp 148 switches on the switch 137 on · Thus, the first series connection is completed and the relay winding 127 energized. As soon as the current intensity in the circuit for the first phase is the previously set exceeds low value, the lamp 143

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switched on and operated the light-actuated controllable silicon rectifier l4l. If the currents of the other phases are also above the previously set low value, the lamps 145 and 147 illuminate the light-actuated controllable silicon rectifier I38 resp. 136 and turn these switches on. Accordingly, the second series connection completed and the second control relay winding 13ο energized. As long as the phase currents are now are between the previously set high and low values, lights 143-148 remain on and the light actuated controllable silicon rectifier 136-142 conductive, whereby the relays 127 and 13o kept in the energized state will. If the phase current in the circuit for any phase exceeds the previously set high value, is that emitted by the corresponding lamp 144, 146 or 148 Light blocked by a movement of the shutter member, so that the light assigned to the lamp was actuated Switch off controllable silicon rectifiers and can make the first control relay winding 127 de-energized. If any Phase current decreases below the previously set low value, that is output by one of the lamps 143, 145 or 147 Light blocked by the movement of the closure member, so that the respectively associated light-actuated controllable silicon rectifier switched off and thus the relay winding 13o is de-energized.

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The control circuit 26 will now be considered. In the lower section of this circuit there is an automatic one Reset timer 76, exactly like that described in the aforementioned U.S. Reissue patent. the to the right of the switch 64 serving to switch between manual and automatic operation C58a and C59a replace the contacts identified in the cited patent with CR2a and CR2b. The one to the right of the Relay winding R2 located contact set CLRa replaces the designation CRIb, and the parallel with the contact set CTR2b switched contact set CTR5a replaces the three original contact sets 52a, 54a and 56a.

The first circuit arranged in the upper part of the control circuit 26 between the lines 117, 118 has the contacts an overload reset pushbutton switch 7o, which is in series with the first winding LR of a locking relay is switched. This means that the set of contacts CLRa immediately to the right of winding R2 when energized the relay winding LR is closed and held in the closed state. When the unlocking winding ULR, which between the lines 117, 118 is connected in series with the contact set CTRl, is energized, the contact set is also CLRa open and remains in the open position. A control lamp 155a is in series between lines 117, 118 switched with the normally open contact set CLRb.

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The winding of the relay TRl is between the lines 117, 118 connected in series with normally closed contact set 127a. The contact set 127a is opened when the relay winding 127 is energized. The relay TRl has a built-in delay, so that between the excitation of the Winding TRl and the closing of the contact set CTRl one short period of time elapses. The winding TR5 is in series with the normally open between lines 117, 118 Contact set 13oa switched. The contact set 13oa is normally closed by the energization of the relay winding 13o. The relay TR5 is of a design in which there is a delay between the switching off of the relay winding and the opening of the associated contact set CTR5a. The delays built into the relays TRl and TR5 prevent the motor feed circuit from being switched off the control circuit 26, if the current in one phase is only briefly greater or less, which otherwise leads to a very brief shutdown of one of the two relay windings 127 or 13o could lead.

To switch on the system, the circuit breaker is first used Io3 closed, so that the three-phase alternating current energy supplied via lines l8-2o via the lines Ioo-lo2 is applied to the open contacts of switch 29. At the same time, the energy of a phase is passed through the transformer 6o are fed to lines 117, 118 of control circuit 26. This energy also goes to the transformer 12o

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ORIGINAL INSPECTED

in the power supply unit Io8 and provides an alternating voltage to the Operation of lamps 143-148 and for actuation of relays 127 » 13o when the associated light-actuated controllable Silicon rectifiers are turned on. At the same time, a circuit is created from the current transformer to the corresponding ones Rectifier bridge circuits 45-47 in the measuring relays completed, but with no power supply to it the measuring relay takes place because the contacts of switch 29 are open. Since the phase currents are all below the previously set are high, the lamps 144, and 148 switch the corresponding semiconductor switches 142, 14o and 137 and complete the first series circuit, which comprises the line 112 and the relay winding 127. The relay is actuated and opens the contact set 127a »whereby the Feed circuit for the relay winding TRl is interrupted. Since the phase currents at this point in time, all below the previously set low value are, none of the light-actuated controllable silicon rectifiers 141, 138 or f 136 conductive, so that the relay 13o is de-energized.

The first time the controller is operated, the overload reset push button switch 7o should be depressed to ensure that the contact set CLRa is not accidentally in the open position. The contact set then remains closed and the overload reset push button switch does not have to be activated every time the system is started up, but only when the system

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has been switched off due to overload.

If it is assumed that the switch 64 for manual operation or automatic operation is in the manual position (upper Position), the one-push button holder 75 is pressed, to complete a feed circuit for winding R2 when the current from line 117 passes through the upper Contact 71 of switch 74, the contacts of switch 75 » the winding R2, the contact set CLRa and the contact set CTR2b to the line 118 flows. Furthermore, a current flows from the One push button switch 75 across winding TR2 to line 118. The operation of the delay relay TR2 is described in the previous paragraph. When the Relay R2, the contact sets CR2c, CR2d, which are arranged parallel to one another and connected to the line 117, are closed. This creates a feed circuit for the relay windings 58, 59 of the main switch is closed, which in switch 29 can operate the six sets of contacts 3oa-31c, i.e. close. By closing these contacts, the supply circuit for the motor 15 is completed, so that the motor accelerates when the phase currents in the lines Ioo-lo2 increase. By actuating the relays 58, 59 are also one behind the other Switched contact sets C58a, C59a closed, which provide a bypass flow path for the one-push button switch 75 to complete. The on-switch 75 has, just like the overload push-button switch 7o, a tension spring which the switch after its actuation in the opening

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position is reset. The one taking place by means of the spring Resetting the one-push button charter therefore leads not to interrupt the supply circuit for the relay winding R2.

Simultaneously with the completion of the supply circuit for the relay winding R2, the relay winding TR2 is also via the Contacts of the one-pressure charter energized. TR2 however, has a built-in delay which, in one embodiment of the invention, can be about 20 seconds and allows the phase currents to exceed the lower set points of the corresponding measuring relays 132-134 can rise. If it is to be assumed that the phase currents are actually are above the lower setting point before the time delay of TR2 has expired, the illuminate Lamps 143, 145 and 147 all light-actuated controllable Silicon rectifiers 142, 138 and 136, so that the second series connection is completed, which the line 114 and the relay winding 13o contains. When the relay 13'o is energized, its contact set 13oa completes a feed circuit for relay TR5, which is immediately excited and closes its contact set CTR5a, which is parallel as shown is switched to the contact set CTR2b. Therefore, when the previously set delay of relay TR2 has expired, The contact set CTR2b opens, but at this point the main switch-on relay winding R2 is via the contact block CTR5a is still excited. If the phase currents come from any

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one reason did not grow above the lower setting value are, both contact sets CTR5a and CTR2b are opened after the time delay of the relay TR2 and switch the System off so that the operator can determine the cause of the failure of the connection.

If the system is in operation and a phase current exceeds the previously set high value, this will be Light of one of the lamps 144, 146 or 148 is dimmed, whereby the first series connection with the winding 127 is interrupted so that the contact set 127a can close and complete the feed circuit for the relay winding TRl. if the high current state is not a brief disturbance and the relay winding 127 before the switch-on delay has expired is not re-energized by TRl, the relay TRl is actuated and its contact set CTRl completes one Supply circuit for the unlocking winding ULR, which opens the contact set CTRa. This becomes the feed circuit for the Main switch-on relay R2 interrupted and the system switched off.

If, in a corresponding manner, a phase current falls below the previously set low value, the relay 13o is switched off and the contact set 13oa opened, whereby the feed circuit for the relay TR5 is interrupted, which one has an effective, built-in delay when switched off. After this delay has elapsed, the contact set opens CTR5a, and since CTR2b is already open, the main switch-on relay R2 is switched off and the system is de-energized.

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The remaining part of the control including the automatic reset by those shown within block 76 Structural members are disclosed in the aforementioned U.S. Patent specification already described.

The economy, the efficiency and the compactness of the invention are also shown in comparison with the control shown in the aforementioned patent specification. In the here under discussion invention, only two relays, i namely the relay 127 and 13o of the overcurrent and undercurrent conditions used to indicate six individual relays are required whereas in the known system. The invention enables fail-safe operation, since failure of a lamp or a light-actuated controlled silicon rectifier leads to the same circuit conditions as an overcurrent or undercurrent of a phase and results in the system being switched off. In addition, only one supply device is required in the arrangement described here, namely the one designated with the reference symbol I08, while in the previous system three separate supply devices, namely one for each phase connection, are required.

- patent claims -

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Claims (5)

- 18 patent claims: lJ Motor control for regulating the supply of a Multi-phase motor through a multi-phase supply circuit with a main switch relay with a winding and main switch contacts for the supply of multiphase energy to the motor, as well as with a current transformer, which is connected in such a way, that it supplies current signals, each of which is a puncture of the current supplied to the motor via a phase line by a display and detector unit (llo) coupled to the current transformer (25) with a measuring relay (132-134) for each phase circuit, the first and second semiconductor switch (142 or 141), the first semiconductor switch in each measuring relay is conductive when the corresponding phase current is below a previously set is high, and the second semiconductor switch in each measuring relay is conductive when the corresponding phase current is above a previously set low value, as well as with a one in series with all first semiconductor switches (142, 14o, 137) switched first line (112) having a first series circuit, which is used to generate a first control signal output, which indicates that all phase currents are below the previously set high value and one in series with all other semiconductor switches (111, I38, I36) switched second line (114) having a second series circuit, which serves a - 19 109812/1 165 to issue a second control signal, which indicates that all phase currents are above the previously set low value, also by a control circuit (26) with a switch-on relay (R2), its winding in series with a switch-on push button switch (75) and one normally closed delay contact set (CTR2b), one used to actuate the delay contact set Delay switch-on relay (TR2), if the phase current exceeds the previously set low value, whereby the The winding of the delay switch-on relay is connected in parallel to a series connection of the switch-on relay winding and the delay contact set, and the main switch relay winding (58, 59) in response to the closure of a contact set (CR2c, CR2d) of the switch-on relay can be actuated to close the main switch contacts (3oa-31c) and switch the motor on To set current, and finally by trip relays (TRl, TR5), which are switched so that they are in the absence of the first or of the second control signal are actuatable to the main switch relay to de-energize and switch off the motor, and a device (I08) for supplying the control. 2. Control according to claim 1, characterized in that the measuring relay (132-134) has two lamps for each phase circle (143-148) and that the first and second semiconductor switches (142, 141; 14o, 138; 137, 136) are connected so that they are normally conductive when the lamps are switched on are, the first series connection is also one 109812/1165 - 2o- ORlGlMAL INSPECTED - 2ο - Control relay winding (127) that is switched on when all phase currents are below the previously set high value lie, and the second series connection also has a second control relay winding (13o) which is switched on, if all phase currents are above the previously set low value. 3. Control according to claim 2, characterized in that the control circuit also has a first trip relay (TRl), whose winding is connected in series with a set of contacts (127a) of the first control relay (127) that the first Steuererrelaiskontaktsatζ when switching off the first control relay closes and completes a circuit for the first trip relay, and the first trip relay as well a set of contacts (CTRl) which is switched so that it is dependent on the actuation of the first trip relay closes and the first switch-on relay (R2) switches off, through which the main switch relay and through this in turn the motor can be switched off, and a second trip relay (TR5) is provided, one in series with a set of contacts (Ij5oa) of the second control relay (13o) has a horizontal winding, so that the contact set of the second control relay is dependent on the shutdown of the second control relay opens and interrupts a supply circuit for the second trip relay, and the second trip relay also one connected in parallel to the delay contact set (CTR2b) - 21 109812/1 165 ORIGINAL INSPECTED and depending on the shutdown of the second The contact set (CTR5a) that opens the trip relay and switches off the switch-on relay, through which the Main switch relay and through this the motor can also be switched off. 4. Control according to claim 1, in particular for a three-phase motor, fed by a three-phase feed circuit the switch contacts of the main switch for the | Supply of three-phase alternating current to the motor are designed, characterized in that the measuring relay has a first and a second light-sensitive semiconductor switch for each phase circuit (142 or I4l), a first lamp (144) in the measuring relay is switched so that it sends a control signal can apply the first semiconductor switch and make it conductive when the respective phase current is below the previously set high value is, and a second lamp (143) in the measuring relay is switched so that it is a> Apply the control signal to the second semiconductor switch and make it conductive when the respective phase current is above the previously set low value, the first series connection is one in series with the first Line (112) and with all first semiconductor holders (142, 14o, 137) connected first control relay winding (127) for the delivery of a serving to excite the first control relay first control signal when all phase currents below - 22 - 1 0 9 8 T 2 / T 1 6 5 - 22 - of the previously set high value, and the second series circuit one in series with the second line (114) and with all the second semiconductor switches (14l, 128, 136) connected second control relay winding (13o) for outputting a to excite the second control relay serving second control signal when all phase currents above the previously set low value. 5. Control according to claims 1-4, characterized in that the trip relay consists of a first trip relay (TRl) and a second trip relay (TR5) exist. 109812/1165